1. Field of Invention
The present invention relates to the field of fabrication and construction. In particular, the invention relates to the fields of plumbing and wiring. More particularly, the invention relates to the installation of pipe, conduit, and other pipe-like material, such as hydraulic and pneumatic tubing. Still more particularly, the invention relates to the accurate bending, for shaping and routing, of pipe, conduit, and other tube-like material in multiple planes.
2. Prior Art
In many fields, it is frequently necessary to bend pipe, conduit, and other tube-like items (hereinafter xe2x80x9cpipexe2x80x9d). The need arises, for example, in the installation of electrical equipment, plumbing systems, and, generally, in construction work. Typically, a single pipe will have to be bent several times. There are two components of the bending process that must be carefully controlled when introducing multiple bends in a pipe: the bend-angle and the bend-plane. Thus, the pipe-bender must be able to accurately measure and control the bend-angle of each bend and the bend-plane, to ensure, for example, that the latest bend is in the desired plane.
It is useful to define a few terms. Reference has been made to a xe2x80x9cbend-plane.xe2x80x9d In order to see what is meant, consider a pipe with no bends in it. There is no plane defined at this point by the pipe regardless of how it is oriented. However, once a single bend introduced in the pipe (resulting in two pipe segments) a bend-plane is defined; it is the plane in which both segments lie (or, more carefully stated, the plane defined by the centerlines of the two segments). This bend-plane of course is only defined with respect to the pipe; its orientation in space is arbitrary and is determined by how the pipe is oriented. When the pipe is laid on a horizontal table, the table will be parallel to the bend-plane; the bend-plane is horizontal. Similarly, if the two-segment pipe is pressed flat against a vertical wall, the bend-plane is vertical.
It can be seen that one does not choose the first bend-plane; it will be defined by the two segments resulting from the bend. However, once that first bend is introduced, a bend-plane has been defined, and a subsequent bend in the pipe is either in that plane or out of it. The second bend will introduce a third segment in the pipe and the potential for two bend-planes, onexe2x80x94the first bend-planexe2x80x94defined by the first and second segment, the otherxe2x80x94the second bend-planexe2x80x94by the second and third segment. Commonly, depending on the use to which the pipe is to be put, it will be desired that the first bend-plane and the second bend-plane are coincident, or, alternately stated, that the second bend-plane lie in the first bend-plane. This would be the case, for example, when the two bends are put in simply to cause an off-set pipe configuration, where all three resulting segments lie in the same plane, and the first and third segments are parallel to one another. Alternatively, it may necessary that the third segment be xe2x80x9cout ofxe2x80x9d the first bend- plane, and that it be out of that plane by a specific angle, and a specific direction.
Although it is important to be able to determine the angle that a pipe segment resulting from a particular bend makes with a particular bend-plane, the most common use for a bend-guide device is to ensure that the segment resulting from a bend is in the bend-plane defined by the previous bend placed in the pipe. If a segment that is supposed to lie in that previously defined bend-plane does not in fact lie in it, one says that it is xe2x80x9cdoggedxe2x80x9d or a xe2x80x9cdogged bendxe2x80x9d (from xe2x80x9cdoglegxe2x80x9d). The difficulty in making accurate multiple bends can be viewed simply in terms of making a second bend in a pipe, that is, in introducing a second bend after a first bend-plane has been defined. For example, inadvertently twisting the pipe or shifting the reference plane between the first and second bends will result in the undesired dogging. Devices for guiding pipe bending so as to control the angle-of-bend and for ensuring that the latest-formed bend segment lies in the previously defined bend-plane are therefore in great demand, as can be seen by the prior art. Since a bend-plane is defined by two adjacent pipe segments xe2x80x9ccreatedxe2x80x9d by a bend, it is useful to also characterize a bend-plane as being defined by the bend (as an alternative to saying that the plane is defined by the two pipe segments that meet at the bend in question).
Simple devices including levels, plumbs, and protractors by themselves, and more elaborate guiding devices employing levels, plumbs, and protractors in combination, have long been employed to introduce bends of pre-determined angles in pipe and then to verify the angle-of-bend and to confirm that the resultant pipe configuration has the desired planarity. Some of these devices attach to the tool being used to bend the pipe and indicate the degree of bend as the pipe-bending tool operates. See, for example, Bergman (U.S. Pat. No. 4,622,837; issued 1986), which teaches the use of a spirit level built into the pipe-bending tool itself to indicate the angle of rotation of the tool from some pre-selected reference direction and, thus, the xe2x80x9cinstantaneousxe2x80x9d angle of bend given to the pipe being bent on the tool. Devices of this type have a serious drawback in that they have no means of indicating or tracking a bend-plane, thereby making it difficult to ensure that a bend being introduced in a pipe lies in the plane defined by a prior bend. In devices like that of Bergman, one makes a subsequent bend in the pipe by sliding the pipe so that the part of the pipe in contact with the pipe-bending tool shifts from the first bend to the position where one desires to place the next bend. During this movement, it is easy to unknowingly twist the pipe enough to get dogging in the next bend, i.e., to cause the next bend segment to jut up out of the plane defined by the first bend. A similar pitfall exists with those guide-equipped tool-bending tools that are removed from the site of a first bend and re-attached to the pipe at the site of the desired second bend.
Traupmann (U.S. Pat. No. 2,824,381; issued 1958) teaches a bend-guide device that, instead of being integrated into the bending tool, is clamped around a segment of a pipe that is to be bent. It appears that the primary function of the Traubmann device is to introduce in-plane offsets into a pipe, the operation by which two bends, of equal angle and opposite sense, are introduced into a pipe so to produce three new pipe segments: a first segment, a second (middle) segment, and a third segment such that all three segments are in the same plane and the first and second segments are parallel to one another. In order to accomplish this task, the guide device of Traubmann must first be mounted on what is to become the middle segment of the offset and then, after the first bend has been introduced, the device must be moved to what is to be the third segment. A major disadvantage of the Traubmann device is that it can indicate direction only for the horizontal projection of the longitudinal axis of the pipe segment to which the device is attached. This means that re-clamping the device for making the second bend can introduce a twist that results in the third segment being out of the plane defined by the first bend. Of course, this problem arises with any bend being guided by the Traubmann device that is supposed to be in a defined plane; this device does not provide any way of ensuring that the bend is indeed in the desired plane. It is also noted that simply having to move and reclamp the Traubmann device is time-consuming. It means that for multiple bends not only does one have to move the pipe-bending tool along the pipe (common to all pipe-bending operations), but one also has to repeatedly reposition the guide device, which in any event does not provide guidance for ensuring that the new bend-plane is coincident with an earlier one.
There do exist recent prior-art devices that attempt to address the need for making several co-planar pipe bends and in particular to ensure that a particular bend is in the same plane as an earlier bend. Weldy et al. (U.S. Pat. No. 5,176,075; issued 1992) discloses such a pipe-bending guide clippable to the open end of a pipe""s end segment. In use, the guide of Weldy et al. is aligned with the longitudinal axis of the end segment of the pipe to be bent, and remains in place throughout the bending operation so as to indicate the relative angle of bend of each of several successive bends. To achieve this, the Weldy et al. device has a spirit level set into a distal section that is pivotable with respect to the proximal section (that section clipped directly to the pipe), pivotable about an axis that is perpendicular to the longitudinal axis of the device. Because of angular markings on the pivot mount, one can pivot that distal section through a selected angle, say xe2x88x9222.5xc2x0. Then one bends the pipe in such a way that the spirit level in that distal section again has its bubble in the center, thus indicating a +22.5xc2x0 bend in the pipe. The device of Weldy et al. addresses the xe2x80x9cco-planarityxe2x80x9d issue through a spirit level mounted fixedly in the proximal section, the axis of this spirit level being perpendicular to the longitudinal axis of the proximal section of the device. This means that this spirit level is also perpendicular to the axis of the pipe segment to which the device is clipped. Before making the first bend, one ensuresxe2x80x94either by rotating the device with respect to the pipe on which it is mounted or by rotating the pipexe2x80x94that the bubble in this spirit level is centered. One ensures further that this bubble remains centered as the first bend is introduced. The device is not moved between bends. Thus, in setting up the next bend and before actually executing it, one ensures that the bubble in this xe2x80x9cperpendicularxe2x80x9d spirit level is again centered. It is by this means that the device of Weldy et al. seeks to establish co-planarity between the two bends, and hence for a series of multiple bends. Although this does help achieve this goal, the Weldy et al. device is limited to bends in the same plane. It does not address the need that often arises wherein a bend is to be out of a plane by a set angle. Furthermore, because of the nature of the means by which it is attached to the pipe, it can inadvertently be xe2x80x9ccockedxe2x80x9d by a few degrees, i.e., as attached to the pipe, its longitudinal axis may not be exactly parallel to the pipe axis, a violation of the condition assumed by the device. (It is noted in passing that even if a means existed for rotating the xe2x80x9cperpendicularxe2x80x9d spirit level by a fixed number of degrees about the longitudinal axis of the pipe, so that rotation of the pipe would set the workpiece up to introduce a desired out-of-plane bend, the modified Weldy et al. device would be incapable of introducing a bend of a pre-selected angle. The reason for this is that with the workpiece set up as described, the axis by which distal end is pivotedxe2x80x94in order to select a bend anglexe2x80x94would not be perpendicular to the next bend plane.)
Mahoney et al. (U.S. Pat. No. 5,154,000; issued 1992) also teaches a device for use in introducing multiple, co-planar bends in a pipe. The device attaches to the end of a pipe segment by means of set screws and may remain in place during several successive bends of the pipe. The Mahoney et al. device uses as a bend-indicator an angle-indicating section having either a spirit level in a housing that is rotatable along the longitudinal axis of the device and marked around its perimeter with a degree scale, or a freely rotating pendulum or plumb set in a housing marked with a degree scale as a means of measuring a bend in the vertical direction (similar to that of the Traupmann device). To address the dogging problem, the Mahoney et al. device contains an xe2x80x9canti-dogxe2x80x9d section that operates in much the same way as the xe2x80x9cperpendicularxe2x80x9d spirit level of the Weldy et al device. The Mahoney et al. device has the same deficiencies as the Weldy et al. device, namely, that it cannot be used to deliberately introduce a dogging angle and it has the propensity to be misaligned when first placed on the pipe segment. In addition, it appears that the set screws of Mahoney et al. may damage the pipe end.
In summary none of the prior-art devices meet the needs of the craftsperson who needs to (1) introduce a number of co-planar bends in a pipe and/or (2) introduce a bend in a pipe that is out of a previously defined plane by a pre-determined angle. Devices such as the one disclosed by Bergman and similar devices that attach to the bending-tool itself do not address at all the problem of ensuring co-planar multiple bends. The devices of Traupmann and Weldy et al. address the anti-dogging problem, but are not able to introduce a specific dogging angle into a bend. The Mahoney et al. device also has the disadvantage of using a two-point location as the mounting means, rather than full-service location. Particularly with larger diameter pipe, such as 6xe2x80x3 pipe, the Mahoney et al. device could introduce an angular error resulting from a cocked mounting of the device at the outset (before bending is commenced). The angular error would be carried forward through all subsequent bends, thus introducing multiple, unintended out-of-plane bends. The Weldy et al. device may also result in a misalignment of the longitudinal axis of the device with the longitudinal axis of the pipe to be bent, as the mounting is a flat-surfaced clamp attaching to a curved pipe wall. Also, the devices of Traupmann and Mahoney et al may damage the pipe to which they attach because they use set screws or other fastening means to mount the device on the pipe.
Therefore, what is needed is a guide for bending pipe that will accurately measure and indicate bend-angles and bend-planes. What is further needed is a such a device that can be secured to the pipe just once at the beginning of the bending operation and not need to be repositioned, regardless of the number of bends and bend-planes to be introduced to a single pipe. What is also needed is such a device the mounting of which on a pipe does not deform the pipe. What is still further needed for efficiency and economy is such a device that has few parts, especially few moving and movable parts.
It is therefore an object of the present invention to provide a pipe-bending guide that will indicate and measure bend angles and enable an operator to control the bend-plane. It is a further object of the present invention to provide such a device that can be secured in position once on a pipe with no need for repositioning or re-aligning, regardless of the number of bends and bend-planes to be given to a single pipe. It is also an object of the present invention to provide such a device the mounting of which on a pipe segment does not deform or damage the pipe. It is a still further object of the present invention to provide an efficient and economical device by incorporating few parts, especially few moving and movable parts.
The device of the present invention is a multiple-bend-angle-and-multiple-bend-plane-guide for use in the bending of pipe. In comparison with the prior-art devices, the device is relatively small and compact. Furthermore, it is inexpensive to manufacture, consisting of relatively few parts. Yet further, the present invention brings to the field of pipe bending the added ability to control the bend-plane in which the angle is introduced. In particular, the device of the present invention enables a bend-tool operator to accurately gauge multiple bends in one or more bend-planes, and to do so without the need to remove and reinstall the guide between bends.
The device incorporates a gauge section ratchet-rotatably attached to a mounting section that clamps onto the end of the pipe to be bent. The mounting section includes a pair of curved jaws that are sized to conform to the respective curvatures of the inner and outer surfaces of the pipe. In addition, the mounting section is provided with a means to tighten the jaws against the pipe wall. The use of such jaws prevents any deformation of the end of the pipe to which the device is attached and, more particularly, ensures that the device is properly and securely located so that the longitudinal axis of the device is aligned parallel to the longitudinal axis of the pipe segment to which the guide is attached.
The gauge section of the device has a bend-plane level and a bend-angle gauge. The bend-angle gauge is a plumb arm depending from a forked plumb mount at a free end of the guide. A degree-indicating scale is mounted or marked on the sides of the forked plumb mount. The plumb arm is free to rotate 360xc2x0 about an axis that runs perpendicular to the longitudinal device axis in the horizontal plane. In the Preferred Embodiment, the bend angle is indicated by a pointer that is fixedly attached to each end of the plumb mount so as to rotate with the plumb arm and point to a marking on a degree scale marked or mounted on the outer sides of the plumb mounting. A desired bend is introduced into the pipe segment by noting the initial reference position indicated by this pointer and then bending the pipe segment until the pointer indicates the desired degree of bend from the reference position. Other means of indicating the bend-angle may also be used. The bend-plane level is a 360xc2x0 spirit level that is mounted on a flat-faced upper end of the plumb arm. Proper alignment of the pipe to a level condition as indicated on the bend-plane level, before the initial bend and with each subsequent bend, and without ever realigning the mount section on the pipe, will ensure that the pipe is bent accurately in the desired bend-plane without xe2x80x9cdoggingxe2x80x9d the bend. To bend the pipe in a different bend-plane, the gauge section, while the device is still mounted on the pipe segment, is rotated relative to the mounting section through an angle equal to the desired xe2x80x9cout-of-plane anglexe2x80x9d and the pipe manipulated (so that the end-segment is rotated) until the bend-plane level again indicates a level condition. The pipe segment is then bent as previously described. It is noted that in contrast to the prior-art devices of Weldy et al. and Mahoney, the device of the present invention contains the bend-angle indicator in the same segment as the bend-plane indicator.
The means for mounting the device of the present invention on the pipe both minimizes the angular error resulting from skewed location of the guide and also prevents damage to the end of the pipe. Because of the nature of the device the bend-tool operator is able to observe the indicators and gauges from a single operating position and to use the guide without assistance and with minimum movement and strain of the operator""s body. Furthermore, incorporating the 360xc2x0 bend-plane level and the plumb arm into a single component reduces the complexity of the device, making it less costly to produce.